Using the Isolated Rat Placenta to Assess Fetoplacental Hemodynamics.

Placental health is critical to fetal growth and maternal health during gestation. However, investigating placental flow in an ex-vivo isolated system where inflow is independently controlled has yet to be developed in the rat. Here, we describe a novel technique, isolated perfused placenta technique that allows for analysis of placental pressure outflow pressure, placental flow in rats at gestational day 20. Using this method, we successfully perfused placentas from dams and were able to observe increases in outflow pressure and flow as the inflow pressure to the placenta was increased in a step wise fashion. This method will help to advance the functional analysis of placental flow and therefore placental resistance and efficiency.

Laser spectroscopy of cooled zirconium fission fragments.

The first on-line laser spectroscopy of cooled fission fragments is reported. The r ions, produced in uranium fission, were extracted and separated using an ion guide isotope separator. The ions were cooled and bunched for collinear laser spectroscopy by a gas-filled linear Paul trap. New results for nuclear mean-square charge radii, dipole, and quadrupole moments are reported across the N=60 shape change. The mean-square charge radii are found to be almost identical to those of the Sr isotones and previously offered modeling of the radial changes is critically reviewed.

On-line ion cooling and bunching for collinear laser spectroscopy.

A new method has been developed for increasing the sensitivity of collinear laser spectroscopy. The method utilizes an ion-trapping technique in which a continuous low-energy ion beam is cooled and accumulated in a linear Paul trap and subsequently released as a short (10-20 micros) bunch. In collinear laser measurements the signal-to-noise ratio has been improved by a factor of 2 x 10(4), allowing spectroscopic measurements to be made with ion-beam fluxes of approximately 50 ions s(-1). The bunching method has been demonstrated in an on-line isotope shift and hyperfine structure measurement on radioactive (175)Hf.

A multivariate analysis of biophysical parameters of tallgrass prairie among land management practices and years.

Six treatments of eastern Kansas tallgrass prairie--native prairie, hayed, mowed, grazed, burned and untreated--were studied to examine the biophysical effects of land management practices on grasslands. On each treatment, measurements of plant biomass, leaf area index, plant cover, leaf moisture and soil moisture were collected. In addition, measurements were taken of the Normalized Difference Vegetation Index (NDVI), which is derived from spectral reflectance measurements. Measurements were taken in mid-June, mid-July and late summer of 1990 and 1991. Multivariate analysis of variance was used to determine whether there were differences in the set of variables among treatments and years. Follow-up tests included univariate t-tests to determine which variables were contributing to any significant difference. Results showed a significant difference (p < 0.0005) among treatments in the composite of parameters during each of the months sampled. In most treatment types, there was a significant difference between years within each month. The univariate tests showed, however, that only some variables, primarily soil moisture, were contributing to this difference. We conclude that biomass and % plant cover show the best potential to serve as longterm indicators of grassland condition as they generally were sensitive to effects of different land management practices but not to yearly change in weather conditions. NDVI was insensitive to precipitation differences between years in July for most treatments, but was not in the native prairie. Choice of sampling time is important for these parameters to serve effectively as indicators.

Pediatric trauma care is cost effective: a comparison of pediatric and adult trauma care reimbursement.

Trauma causes staggering losses: in 1987, Hermann Hospital lost $8 million to uncompensated trauma care. To demonstrate the survivability of pediatric trauma care delivery we examined reimbursement profiles for adult and pediatric trauma patients. We retrospectively reviewed the records of 3445 patients with serious trauma from October 1987 through March 1992. The group was divided into adult (> or = 17 years) and pediatric patients (< 17 years). We compared reimbursement profiles based on hospital costs generated, reimbursement, financial class, demographics, discharge diagnostic codes, and outcome. Significance was assessed by t test and Chi-square. We found a decreased length of stay (LOS) and a lower association with under-reimbursement or zero reimbursement in pediatric patients. A significantly lower percentage of pediatric patients paid none of their bill (17.1%) compared with the adults (23.2%). Pediatric reimbursement exceeded hospital costs (110.0%) compared with adult reimbursement (90.3%). This suggests that pediatric trauma care can survive in an atmosphere of shrinking resources.

Kinetics and thresholds of several indices of lindane-induced toxicity.

The effects of lindane, administered either IP (4, 6 or 8 mg/kg in dimethylsulfoxide, 0.5 ml/kg) or PO (30, 40 or 50 mg/kg in oil, 1 ml/kg), were compared in male rats. Effects appeared later and lasted longer after PO administration. After either route, convulsant effects occurred first and were over before hypothermic effects were maximal. Also, hypothermia subsided before hypophagia ended. After IP administration, hypothermia had the lowest threshold and convulsions the next lowest; reduced food intake was produced only by the highest dose, which also produced 43% deaths. By contrast, after PO administration, all doses reduced food intake and produced hypothermia, but deaths did not occur after even the highest dose. The different time courses and thresholds for the different indices of toxicity suggest that different target sites or mechanisms may be involved. Thus, effects on the gut, in addition to effects on the brain, may account for the longer duration and greater sensitivity of reduced food intake, compared to lethal and hypothermic effects, after PO administration of lindane. After administration of lindane IP, peripheral vasodilation (as demonstrated by an increase in tail temperature) preceded colonic hypothermia. This could be explained if lindane inappropriately activated heat-loss mechanisms.

"Central" and "peripheral" benzodiazepines and kinetics of lindane-induced toxicity.

Because hypothermia and anorexia were previously found to be more sensitive indices of the effects of lindane than were convulsions, these endpoints were used to quantify the ability of benzodiazepines (BDs) and phenytoin either to ameliorate or exacerbate the toxicity of lindane in the rat. After administration of lindane (40 or 50 mg/kg) in oil per os, toxicity was counteracted by phenytoin and the "central" BD agonists diazepam and clonazepam, but was worsened by Ro 5-4864 a "peripheral" BD agonist. Clonazepam and diazepam were each more effective in counteracting lindane-induced anorexia than in stimulating food intake, presumably because the animals had been fasted and probably even controls ate maximally when food was presented. Diazepam alone (3 injections in 1 day) produced withdrawal-induced decreased food intake the following day. Clonazepam and diazepam alone each transiently decreased colonic temperature, yet effectively blocked the more severe hypothermia produced by lindane. Ro 5-4864 by itself did not produce any measurable effects, yet exacerbated all of the effects, including lethal effects, of lindane. The present findings are compatible with other evidence that lindane and Ro 5-4864 act at the picrotoxinin receptor of the GABAA-activated chloride channel and that systemic administration of agents acting at this site may produce a constellation of effects, including seizures, hypothermia and anorexia.

Peroral extrusion of a ventriculoperitoneal shunt catheter.

A case of retrograde migration and peroral extrusion of a ventriculoperitoneal catheter is reported. A patient population at risk is defined, and preventive measures are discussed.

An attractive career opportunity--industrial health.

As health care delivery moves away from the acute care setting, so moves the MRA graduate. The entry-level graduate of today should be looking more at nontraditional health care settings for career opportunities. One such setting which can provide an attractive working environment for graduates is discussed in this article.